1996 GMC Sierra Popping noise only when decelerating

JDW3399

MEMBER

1996 GMC SIERRA

V8

4WD

AUTOMATIC

115,000 MILES

I have a relatively low mileage K3500, DRW, 4 WD, diesel, AT. Only when decelerating - I hear popping noises in the front/center. Generally happens from 50 MPH down to about 40. Braking alone does not affect. Holding foot on brake and continuing to "accelerate" or keep foot on gas does affect/eliminate noise. Transaxle and differentials have been serviced and truck has been lubed regularly. Noises began after truck was not driven for several months and seem to happen more frequently than when first started. Probable cause? Danger of continuing to drive?

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Wednesday, November 4th, 2009 AT 8:34 AM

5 Replies

JACOBANDNICKOLAS

EXPERT

I would start by checking u-joints and axle joints. Have you had a chance to check them? Also, does it sound like the sound is from the drive line or the engine?

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Wednesday, November 4th, 2009 AT 8:56 PM

JDW3399

MEMBER

Have visually inspected u-joints and looked for problems with axle joints without removing axles or boots. Definitely a drive line noise. Mechanic wants to begin replacing axles (he thinks noise is on one side of center and I think it comes from other). Had heard that sometimes clutches or something in 4 WD unit could malfunction and cause noises. Any use in pulling axles, lubricating cv joints and reinstalling with new boots - or should I just replace axles? What is danger of keeping on driving until problem gets bad enough to easily tell what is going wrong?

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Thursday, November 5th, 2009 AT 7:38 AM

JACOBANDNICKOLAS

EXPERT

Without knowing the problem, I can't say how safe it is. Regardless, with the vehicle in the air (on a rack) has the mechanic tried to duplicate the sound with the vehicle running and in gear?

As far as repairing a bad joint, anymore axles have become much cheaper to purchase. With the high labor rates, it works out to about the same price between repair -vs- replacement. Go with the new parts.

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Thursday, November 5th, 2009 AT 7:55 AM

JDW3399

MEMBER

No - have not run truck in gear on lift - noise is only present when decelerating from 50 MPH.

Thanks - just figured someone else had heard the popping noise on deceleration only and could tell me what they had done to fix. Most info on replacing axles has to do with noise when turning. My truck makes no noises when turning, accelerating, normal driving - only when I take my foot off the throttle. Guess I will start replacing parts and hope for the best.

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Thursday, November 5th, 2009 AT 9:27 AM

JDW3399

MEMBER

I have replaced both CV axles and the Pitman arm. Noise is still the same or maybe getting worse. Did try running engine in gear on lift but could not duplicate the noise. Cannot find other worn parts. Definitely a drive line noise. Not exhaust or brakes. Again - only present during coasting - not present during acceleration.